There are a number of well-known diagnostic imaging techniques that allow a physician to obtain high fidelity views of the human body. Imaging systems which provide cross-sectional (tomographic) views of anatomical structure without invasive procedures include computed tomography (CT) x-ray imagers and magnetic resonance (MR) imagers.
A problem associated with the scanning techniques is that each imaging process is sensitive to the patient's position within the imaging device. Therefore, each set of images has a discrete, unique orientation. Thus, images formed from the same modality at different times and images formed at essentially the same time, but from different imaging modalities (for example, CT and MRI) cannot be compared on a point-by-point basis. This prevents accurate comparison of regions within the images.
A surgeon also deals with orientation differences to the imaging space. For example, although a neurosurgeon will know where his surgical tool is with regards to certain anatomic landmarks he may not know with the desired precision where the tool is with regards to the lesion visible on the images. There have been attempts to solve this problem by temporary attachment of a relatively large brace-like structure surgically attached to portions of the body, such as the head. By orienting a surgical tool with respect to this structure, and by knowing the location of internal anatomical areas of interest with relation to this attached structure, the position of the surgical tool with respect to the anatomical areas of interest will be known.
A problem with these structures is their size and their interference with normal daily activities, such as sleeping The structures are therefore not used over a long period of time (e.g. for more than 12 hours) so that a comparison of images, or the location of a specific point within the anatomy, taken over a substantial time period is not practical.
There is therefore a need for an interactive system which will guide a surgeon in the manipulation of a surgical tool to an exact location that is specified by an imaging system.